It has hitherto been known that sintered materials are obtained by using pure iron powder as a main starting material. However, the tensile strength of such a sintered material is about 30-40 kgf/mm.sup.2, which is a low level of mechanical strength, so that the application thereof is undesirably restricted to low load pulleys and the like.
As a means for solving the above drawback, there is developed a technique of utilizing an alloy steel powder obtained by soluting various alloying ingredients such as Mn, Ni, Cr and Mo into powdery particles (for example, reference may be made to Japanese patent application publication No. 49-28,827).
In such an alloy steel powder, however, it is possible to raise the strength of steel powder itself through alloying, but the plastic deformation in the forming process becomes difficult with the rise of the strength to impede the compressibility, and it is necessary to degrade the strength of the sintered body due to the reduction of the sintered density. Therefore, the resulting sintered body has not sufficient mechanical properties.